Secure human fingerprint sensor

ABSTRACT

Devices, systems, and techniques are provided for performing human fingerprint detection and authentication for authenticating a request to access a locked mobile device equipped with a fingerprint detection module. In one aspect, responsive to detecting a contact from an object with the fingerprint detection module, described technique can be used to determines whether the contact from the object is from human skin. When determined that the detected contact from the object is from human skin, a presence of a human fingerprint can be detected from the object making contact. The detected fingerprint data can be obtained from the object and compared against stored fingerprint profiles associated with an authorized user of the locked mobile device. Based on the comparing, the request to access the locked mobile device can be granted.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent document is a divisional application of U.S. patentapplication Ser. No. 14/552,459, filed on Nov. 24, 2014, which claimsthe benefits and priorities of U.S. Provisional Patent Application No.61/908,026, filed on Nov. 22, 2013 and U.S. Provisional PatentApplication No. 62/031,833, filed on Jul. 31, 2014. The entire contentsof the before-mentioned patent applications are incorporated byreference as part of the disclosure of this document.

TECHNICAL FIELD

The patent document relates to fingerprint recognition for securelyaccessing a mobile device.

BACKGROUND

Electronic devices including portable or mobile computing devices, suchas laptops, tablets, smartphones, and gaming systems, may employ userauthentication mechanisms to protect personal data and preventunauthorized access. User authentication on an electronic device may becarried out through one or multiple forms of biometric identifiers,which can be used alone or in addition to conventional passwordauthentication methods. A popular form of biometric identifiers is aperson's fingerprint pattern. A fingerprint sensor can be built into theelectronic device to read a user's fingerprint pattern so that thedevice can only be unlocked by an authorized user of the device throughauthentication of the authorized user's fingerprint pattern.

SUMMARY

Embodiments described in this document provide devices, systems, andtechniques that perform human fingerprint detection and authenticationfor authenticating an access attempt to a locked mobile device equippedwith a fingerprint detection module. In one aspect, a disclosedfingerprint detection system includes a touch sensing module whichincludes a touch sensor (such as a metal ring) and a sensor circuit fordetecting an object making contact with fingerprint detection system; anoptical sensor module including one or more light emitting sources andat least one photodetection element, a fingerprint pattern sensor, andan authentication processor. The touch sensing module is coupled to theoptical sensor module. If the touch sensing module detects an object,such as a finger, the touch sensing module activates the optical sensormodule, which then produces probe light at two or more different opticalwavelengths to which a person's skin produces different opticalresponses at the two or more different optical wavelengths due topresence of blood in the person's skin. The optical sensor module alsoincludes an optical detection unit that receives a reflection ortransmission of the probe light to produce optical measurements of theprobe light at the two or more different optical wavelengths. Theoptical measurements at different wavelengths can then be used tocompute values that are compared to standard or calibrated values forhuman blood absorption to determine if the object is human skin. Thecomputation, comparison, and determination operations can be performedby an on-chip signal processing unit integrated with the optical sensormodule.

Moreover, the optical sensor module is coupled to the fingerprintpattern sensor. If the optical sensor module detects human skin as theobject making contact, the optical sensor module activates thefingerprint pattern sensor, which includes a sensor array for gatheringfingerprint data and a fingerprint pattern processor for determiningwhether the gathered fingerprint data resembles a human fingerprint. Thefingerprint pattern sensor is coupled to an authentication processor. Ifthe fingerprint pattern sensor detects a human fingerprint, thefingerprint pattern sensor activates the authentication processor. Theauthentication processor receives the gathered fingerprint data from thefingerprint pattern sensor and authenticates the gathered fingerprintdata against stored fingerprint data of an authorized person'sfingerprint pattern, and based on the verification outcome to generateauthorization output to either grant or deny the access attempt.

In a high security operation mode, the authentication processor can alsoreceive the optical measurements at the two or more optical wavelengthsfrom the optical sensor module, and used the optical measurements todetect a human heartbeat signal. This heartbeat detection offers anadditional check on whether a live person is associated with thedetected human fingerprint. The authentication processor then generatesan authorization decision based on both the result of fingerprintauthentication and the result of heartbeat detection.

In one aspect, a technique for authenticating an access attempt to alocked mobile device equipped with a fingerprint detection moduleincludes detecting whether an object is making contact with thefingerprint detection module. When determined that the object is makingcontact with the fingerprint detection module, the technique can be usedto determine whether the object is human skin, and when determined thatthe object is human skin, the techniques can be used to furtherdetermine whether the object resembles human fingerprint associated withan access attempt. When a human fingerprint is confirm, the techniquecan be used to gather fingerprint data from the object; authenticate thegathered fingerprint data against stored fingerprint profiles; and grantor denying the access attempt based on the outcome of the gatheredfingerprint authentication.

In another aspect, a technique for authenticating an access attempt to alocked mobile device equipped with a fingerprint detection moduleincludes, in response to detection of an object making contact with thefingerprint detection module, determining whether the object is humanskin. When determined that the object is human skin, the technique canbe used to determine whether the object resembles human fingerprintassociated with an access attempt. When human fingerprint is confirmed,the technique can be used to gather fingerprint data from the object andauthenticating the gathered fingerprint data against stored fingerprintprofiles. When the gathered fingerprint data is authenticated as a validfingerprint, the technique can be used to determine whether the objectis associated with a heartbeat signal. When determined that the objectis associated with a heartbeat signal, the access attempt is granted.Otherwise, the access attempt is denied.

In another aspect, a technique for authenticating an access attempt to alocked mobile device equipped with a fingerprint detection moduleincludes detecting whether an object is making contact with thefingerprint detection module. When determining that the object is makingcontact with the fingerprint detection module, the technique can be usedto determine whether the object is human skin. When determined that theobject is human skin, the technique can be used to gather fingerprintdata from the object and authenticate the gathered fingerprint dataagainst stored fingerprint profiles. When the gathered fingerprint datais authenticated as a valid fingerprint, the technique can be used todetermine whether the object is associated with a heartbeat signal. Whendetermined that the object is associated with a heartbeat signal, theaccess attempt is granted. Otherwise, the access attempt is denied.

In yet another aspect, a fingerprint detection module includes asubstrate carrier and a fingerprint sensor chip located on the substratecarrier for collecting fingerprint data. The fingerprint detectionmodule also includes a protective cover placed over the fingerprintsensor chip to protect the fingerprint sensor chip and a metal ringplaced around the protective cover as a touch sensor to detect if anobject is making contact with the fingerprint detection module. Thefingerprint detection module additionally includes an optical detectionmodule that contains: one or more light emitting sources located on thesubstrate carrier and underneath the protective cover; at least onephotodetection element located on the substrate carrier and underneaththe protective cover; and a signal processing circuit integrated withthe fingerprint sensor chip. The fingerprint detection module furtherincludes a colored layer coated on the bottom surface of the protectivecover, wherein the colored layer contains micro-holes in a first regiondirectly above the one or more light emitting sources and a secondregion directly above the at least one photodetection element to allowlight to pass through the colored layer in the first region and thesecond region.

In yet another aspect, a fingerprint detection system includes a touchsensor which contains a metal ring for detecting an object makingcontact with the fingerprint detection module. The fingerprint detectionsystem also comprises a fingerprint pattern sensor that includes asensor array which reads a fingerprint pattern and a fingerprint patternprocessor that determines whether the received fingerprint patternmatches stored information of an authorized person's fingerprint patternto provide a fingerprint pattern authentication output. The fingerprintdetection system additionally includes an optical sensor module thatproduces probe light at two or more different optical wavelengths towhich a person's skin produces different optical responses at the two ormore different optical wavelengths due to presence of blood in the skin,the optical sensor module including an optical detection unit thatreceives a reflection or transmission of the probe light to produceoptical measurements of the probe light at the two or more differentoptical wavelengths. Moreover, the fingerprint detection system includesan authentication processor that receives the fingerprint patternauthentication output from the fingerprint pattern sensor and theoptical measurements of the probe light at the two or more differentoptical wavelengths from the optical sensor module and to combine boththe fingerprint pattern authentication output and optical measurementsof the probe light to determine whether an access is to be granted ordenied.

Various examples of fingerprint detection modules and fingerprint sensormodules described in this patent document can be integrated with mobiledevices (e.g., smartphones, tablets, laptops), computing devices (e.g.,personal computers), and other electronic devices to perform fingerprintauthentication processes on these devices.

In yet another aspect, a method is provided for authenticating a requestto access a locked mobile device equipped with a fingerprint detectionmodule to include obtaining measurements of (1) a contact provided by aperson and (2) a fingerprint input from the same person; determiningwhether the detected contact provided by the person is from a liveperson; comparing the fingerprint data from the obtained fingerprintinput against one or more stored fingerprint profiles associated with anauthorized user of the locked mobile device; and determining granting ordenying the person's access based on both of (1) whether there is matchin the fingerprint data and (2) whether the detected contact indicatesthe contact is from a live person.

The above and other aspects of the disclosed technology and theirimplementations and examples are described in greater detail in thedrawings, the description and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic of a cross-sectional view of a fingerprintdetection module.

FIG. 2 shows a schematic of an exemplary fingerprint sensor detectorchip.

FIG. 3A shows a perspective and cross-sectional view of a fingerprintdetection module which includes an optical sensing mechanism fordetermining whether a detected object is human.

FIG. 3B provides another perspective and cross-sectional view of thefingerprint detection module in FIG. 3A.

FIG. 3C provides a perspective view of the entire fingerprint detectionmodule in FIG. 3A.

FIG. 4 illustrates the concept of using a fingerprint detection moduleto detect and determine if a detected object is human.

FIG. 5A shows a data plot of normalized human skin reflectance (in %) asa function of wavelength of the light source.

FIG. 5B shows a data plot of human blood light absorption property (inextinction coefficient) as a function of the wavelength of the lightsource.

FIG. 6A presents a flowchart illustrating a process of using afingerprint detection module to detect and determine if a detectedobject is human.

FIG. 6B presents a flowchart illustrating a process of using afingerprint detection module having a metal ring circuit for fingerprintdetection and authentication.

FIG. 7 presents a diagram of a fingerprint detection module forperforming human fingerprint detection and authentication.

FIG. 8A shows a schematic of a mobile device integrated with a touchpanel and a fingerprint detection module.

FIG. 8B shows a schematic of another mobile device integrated with atouch panel and a fingerprint detection module.

FIG. 9A presents a flowchart illustrating a process of activating afingerprint detection module in standby mode and using the fingerprintdetection module to authenticate an access attempt to a locked mobiledevice.

FIG. 9B presents a flowchart illustrating a process of activating afingerprint detection module in standby mode and using the fingerprintdetection module to authenticate an access attempt to a locked mobiledevice in a highly secure mode.

FIG. 10 presents a flowchart illustrating a process of using thefingerprint detection module to authenticate an access attempt to alocked mobile device through a highly secure procedure.

FIG. 11A illustrates a fingerprint detection module as a variation offingerprint detection module for detecting and determining whether adetected object is human.

FIG. 11B illustrates a fingerprint detection module which includes aprotective cover coated with a colored layer.

FIG. 12 presents a diagram of a fingerprint detection system forperforming human fingerprint detection and authentication.

FIG. 13A is a top-down view of an exemplary mobile device showing atouch sensor assembly packaged under a display screen cover glass.

FIG. 13B is a cross sectional view of the mobile device cut along theline A-A.

FIG. 13C shows a cross-sectional view of the touch sensor assembly shownin FIGS. 13A and 13B packaged to be under or flush with the displayscreen cover glass 1310.

DETAILED DESCRIPTION

Electronic devices equipped with fingerprint authentication mechanismsmay be hacked by malicious individuals who can obtain the authorizeduser's fingerprint, and copy the stolen fingerprint pattern on a carrierobject that resembles a human finger, which can then be used to unlockthe targeted device. Hence, the fingerprint pattern, although a uniquebiometric identifier, may not be by itself a completely reliable orsecure identification. The techniques, devices and systems described inthis document improve upon, or augment, a fingerprint authenticationtechnology used in electronic devices by providing an additional sensingmechanism for determining whether the detected contact from the objectis from a live person to potentially prevent a stolen fingerprint frombeing used to gain access to the targeted device.

In some embodiments, a touch sensing module that includes a touch sensor(e.g., implemented using a metal ring or other similar conductivematerials and structures) placed around a fingerprint detection moduleon a mobile device and associated touch sensing circuitrycommunicatively coupled to the touch sensor can be used to detect acontact from an object with the touch sensor, such as the metal ring andthe fingerprint detection module. The touch sensing module can be usedto activate the fingerprint detection module and the mobile device in apower saving/standby mode with a light touch, without additional userinput such as actuating a mechanical switch or button. However, ineveryday uses when a user is holding or carrying (e.g., in a pocketclose to the body) a mobile device, unintended and incidental contactthe touch sensing module are common and can be difficult to avoid. Itcan be undesirable from power saving perspective if any contact by afinger or a part of the human body with the touch sensing moduleindiscriminately activates the fingerprint detection module and/or themobile device in power saving/standby mode. Embodiments described inthis document provide devices, systems, and techniques that enable lighttouch activations of fingerprint detection module while preventing orreducing unintended and incidental touches from activating thefingerprint detection module and/or the mobile device in a standby mode.

Embodiments described in this document provide devices, systems, andtechniques that perform human fingerprint detection and authenticationfor authenticating a user requesting to gain access to a locked mobiledevice equipped with a fingerprint detection module. In one aspect, afingerprint detection system includes a touch sensing module whichincludes a touch sensor (such as a metal ring) and a sensor circuitryfor detecting an object making contact with the fingerprint detectionsystem; an optical sensor module, a fingerprint pattern sensor, and anauthentication processor. The touch sensing module is communicativelycoupled to the optical sensor module. Responsive to the touch sensingmodule detecting a contact from an object, such as a finger, the touchsensing module activates the optical sensor module, which then producesprobe light signals at two or more different optical wavelengths towhich a person's skin produces different optical responses at the two ormore different optical wavelengths due to presence of blood in theperson's skin. The optical sensor module includes an optical detectionunit that receives a reflection or transmission of the probe lightsignals to produce optical measurements of the probe light signals atthe two or more different optical wavelengths. The optical measurementsat different wavelengths can then be used to compute values that arecompared to standard or calibrated values for human blood absorption todetermine whether the detected contact from the object is from humanskin. The computation, comparison, and determination operations can beperformed by an on-chip signal processing unit integrated with theoptical sensor module.

Moreover, the optical sensor module is coupled to the fingerprintpattern sensor. Responsive to the optical sensor module detecting thatthe contact is from human skin, the optical sensor module activates thefingerprint pattern sensor, which includes a sensor array for gatheringfingerprint data and a fingerprint pattern processor for determiningwhether the gathered fingerprint data resembles a human fingerprint. Thefingerprint pattern sensor is communicatively coupled to anauthentication processor. Responsive to the fingerprint pattern sensordetecting a human fingerprint of a user requesting access to the lockedmobile device, the fingerprint pattern sensor activates theauthentication processor. The authentication processor receives thegathered fingerprint data from the fingerprint pattern sensor andattempts to authenticate the user by comparing the gathered fingerprintdata against stored fingerprint data of an authorized user's fingerprintpattern. Based on the result of the attempted authentication, theauthentication processor can generate an authorization decision toeither grant or deny access to the locked mobile device.

In a high security operation mode, the authentication processor can alsoreceive optical measurements at two or more optical wavelengths from theoptical sensor module, and use the received optical measurements todetect a human heartbeat signal. The optical heartbeat detection canpotentially offer an additional verification on whether a live user isassociated with the detected human fingerprint. The authenticationprocessor then generates an authorization decision based on both theresult of the fingerprint comparison and the result of optical heartbeatdetection.

In one aspect, a technique for authenticating a user requesting to gainaccess to a locked mobile device equipped with a fingerprint detectionmodule includes detecting a contact from an object on the fingerprintdetection module. Responsive to determining that the detected contactfrom the object is from human skin, the technique can be further used todetermine whether the detected contact from human skin resembles contactfrom a human fingerprint associated with a user requesting to access thelocked mobile device. Responsive to determining that the detectedcontact is from a human fingerprint, the technique can be used to obtainfingerprint data from the human skin. The obtained fingerprint data canbe compared against stored fingerprint profiles in an attempt toauthenticate the user, and user access to the locked mobile device canbe granted when the obtained fingerprint matches one of the storedfingerprint profiles associated with an authorized user of the lockedmobile device.

In another aspect, a technique for authenticating a user requestingaccess to a locked mobile device equipped with a fingerprint detectionmodule includes, in response to detecting a contact from an object withthe fingerprint detection module, determining whether the detectedcontact from the object is from human skin. Responsive to detecting thecontact from human skin, the technique can be used to determine whetherthe detected contact from human skin resembles contact from humanfingerprint associated with a user requesting an access to the lockedmobile device. Responsive to determining that the contact is from humanfingerprint, the technique can be used to obtain fingerprint data fromthe human fingerprint and attempt to authenticate the user by comparingthe obtained fingerprint data against stored fingerprint profiles of anauthorized user. Responsive to matching the obtained fingerprint datawith stored fingerprint profiles of an authorized user, the techniquecan be used to subsequently determine whether the detected object isassociated with a heartbeat signal. Responsive to associating aheartbeat with the detected object, user access is granted. Otherwise,the access attempt is denied.

In another aspect, a technique for authenticating a user requestingaccess to a locked mobile device equipped with a fingerprint detectionmodule includes detecting a contact from an object with the fingerprintdetection module. Responsive to detecting the contact, the technique canbe used to determine whether the contact from the object is from humanskin. Responsive to detecting contact from human skin, the technique canbe used to obtain fingerprint data from the human skin and compare theobtained fingerprint data against stored fingerprint profiles of anauthorized user. Responsive to finding a match between the obtainedfingerprint data and the stored fingerprint profiles of an authorizeduser, the obtained fingerprint is identified as a valid fingerprint ofan authorized user. The technique can be used to subsequently determinewhether the object making contact is associated with a heartbeat signal.Responsive to detecting a heart beat signal from the human skin having afingerprint, the user access is granted. In absence of both fingerprintdetection and heartbeat detection, the user access attempt is denied.

In yet another aspect, a fingerprint detection module includes asubstrate carrier and a fingerprint sensor chip located on the substratecarrier for collecting fingerprint data. The fingerprint detectionmodule also includes a protective cover placed over the fingerprintsensor chip to protect the fingerprint sensor chip and a touch sensorplaced around the protective cover to detect a contact from an objectwith the fingerprint detection module. The touch sensor can be made of aconductive material that borders at or near an outline of the protectivecover and can be shaped to conform with the outline of the protectivecover. For a round protective cover, the touch sensor can be a metalring for example. For a rectangular protective cover, the touch sensorcan be a metal rectangular frame for another example. Also, thefingerprint detection module includes an optical detection module thatcontains: one or more light emitting sources located on the substratecarrier and underneath the protective cover; at least one photodetectionelement located on the substrate carrier and underneath the protectivecover; and a signal processing circuit integrated with the fingerprintsensor chip. In addition, the fingerprint detection module includes acolored layer coated on the bottom surface of the protective cover. Thecolored layer contains micro-holes in a first region directly above theone or more light emitting sources and a second region directly abovethe at least one photodetection element to allow light to pass throughthe colored layer in the first region and the second region.

In yet another aspect, a fingerprint detection system includes a touchsensor such as a metal ring to detect a contact from an object with thefingerprint detection module. Also, the fingerprint detection systemincludes a fingerprint pattern sensor to detect a fingerprint pattern.The fingerprint patter sensor can be implemented using a sensor array,for example. The fingerprint detection system can include a fingerprintpattern processor to determine whether the detected fingerprint patternmatches stored information of an authorized person's fingerprint patternto provide a fingerprint pattern authentication output. Also, thefingerprint detection system includes an optical sensor module toproduce probe light signals at two or more different optical wavelengthsto which a user's skin produces different optical responses at the twoor more different optical wavelengths due to the presence of blood inthe skin. The optical sensor module includes an optical detection unitto receive a reflection or transmission of the probe light signals toproduce optical measurements of the probe light signals at the two ormore different optical wavelengths. Moreover, the fingerprint detectionsystem includes an authentication processor to receive the fingerprintpattern authentication output from the fingerprint pattern sensor andthe optical measurements of the probe light signals at the two or moredifferent optical wavelengths from the optical sensor module. Thefingerprint detection system can combine both the fingerprint patternauthentication output and optical measurements of the probe lightsignals to determine whether an access is to be granted or denied.

Embodiments described in this document provide devices, systems, andtechniques that implement various fingerprint detection modules forhuman fingerprint detection and authentication. Moreover, embodimentsdescribed in this document provide devices, systems, and techniques thatimplement various fingerprint detection modules including an opticalsensing unit to determine if a detected object is human. Specifically,the technology disclosed in this document uses an additional measurementor sensing mechanism to make another measurement beyond the fingerprintsensing obtained from a person to combine with detection of the person'sfingerprint pattern as a combination authentication method to identifywhether the authorized person is accessing the device.

The disclosed technology uses probe light at two or more different probelight wavelengths in the additional sensing mechanism where the humanskin provides different optical responses at the two or more differentwavelengths. Measurements of such optical responses at the two or moredifferent wavelengths are used to combine with the positiveidentification of the person's fingerprint pattern to authenticate theaccess. This additional layer of authentication can improve the level ofauthentication and the security that may not be possible by using thefingerprint pattern alone. In the specific examples described below, thetwo or more different probe light wavelengths may be selected so thatreflectance or absorption of the person's skins due to presence of theblood in the skin and the oxygen level in the blood to cause differentoptical responses in the reflected light or transmitted light at theselected two or more different wavelengths. In implementation, thedevice can include two sensor devices: (1) a fingerprint patternrecognition sensor and (2) an optical detection module for producingprobe light of two or more different wavelengths and for measuring thereflectance or transmission of the probe light of the finger to measurethe optical responses of the finger at the two or more differentwavelengths. The measurements from the two sensor devices are combinedto authenticate a person for accessing the device. In implementations,those two sensor devices can be integrated into a fingerprint ID modulelocated on a surface of a device to enable a user to input the user'sfingerprint when accessing the device. The appearance of such afingerprint ID module may be similar to other fingerprint ID moduleswhere only fingerprint patterns are detected and processed but theadditional optical detection module based the measurements of probelight of two or more different wavelengths provides a unique addedsecurity and accuracy in granting proper user access to the device.

FIG. 1 shows a schematic of a cross-sectional view of a fingerprintdetection module 100 (finger is not included). As shown in FIG. 1,fingerprint detection module 100 includes a substrate carrier 102 and afingerprint sensor detector chip 104 affixed on top of substrate carrier102. Fingerprint sensor detector chip 104 can use capacitive sensing tocollect fingerprint data and detect fingerprints. However, fingerprintsensor detector chip 104 can also be configured to collect fingerprintdata and detect fingerprints by non-capacitive means. Fingerprintdetection module 100 also includes a protective cover 106 which isplaced over fingerprint sensor detector chip 104 to protect fingerprintsensor detector chip 104 and can also serve as a dielectric spacer.Protective cover 106 may be made out of high dielectric-constantmaterial, such as ceramic, sapphire, zirconia, among others. Protectivecover 106 may also have a hard coating, such as diamond like carbon.Note that in the embodiment of FIG. 1, the edges of protective cover 106extends beyond the edges of fingerprint sensor detector chip 104 in alldirections.

Fingerprint detection module 100 additional includes a metal ring 108placed on substrate carrier 102 and around protective cover 106, whichprotects the edge of protective cover 106 and can also serve as a signalelectrode. Note also that a finger 110 (not part of fingerprintdetection module 100) can make contact with metal ring 108 when finger110 is pressed on fingerprint detection module 100 for fingerprintdetection.

FIG. 2 shows a schematic of an exemplary fingerprint sensor detectorchip 200. Note that fingerprint sensor detector chip 200 (or “sensorchip 200”) may be used as sensor chip 104 in fingerprint detectionmodule 100 or in combination with other types of fingerprint detectionmodules described below.

As shown in FIG. 2, fingerprint sensor detector chip 200 comprises apixelated sensing element array 202 which occupies a significant portionof the sensor chip. Each sensing element in pixelated sensing elementarray 202 may be a CMOS capacitive sensor or other types of sensorscapable of sensing fingerprint features. Fingerprint sensor detector canalso include a signal processing unit 204 for processing signalsreceived from pixelated sensing element array 202, and a connection unit206 coupled to signal processing unit 204. Connection unit 206 mayinclude multiple electrodes which can be connected to external circuitrythrough wire-bonding, bump bonding or other connection means. Connectionunit 206 may be situated along an edge of sensor chip 200 for theconvenience of interfacing with other components of a fingerprintdetection module.

Note that sensor chip 200 also includes one or more photodetectionelements 208, which may be located at one or more sections of sensorchip 200. Photodetection elements 208 can include, but are not limitedto CMOS photodetectors, charge-coupled devices (CCD) photodetectors,light-emitting diode (LED) photodetectors, photoresistors, photovoltaicphotodetectors, and photodiodes. In the embodiment shown, there are twophotodetection elements located along one edge section of the sensorchip. In one embodiments, there can be just a single photodetectionelement or more than two photodetection elements. The multiplephotodetection elements may be located at different edge sections of thesilicon chip instead of all on the same side of the chip. Note thatwhile FIG. 2 shows that photodetection elements 208 are integrated withpixelated sensing element array 202 on the same chip, other embodimentscan have the photodetection elements off the sensor chip on a differentarea of the fingerprint sensor module.

FIG. 3A shows a perspective and cross-sectional view of a fingerprintdetection module 300 which includes an optical sensing mechanism fordetermining whether a detected object is human. Similarly to fingerprintdetection module 100, fingerprint detection module 300 includes asubstrate carrier 302, a fingerprint sensor detector chip 304, aprotective cover 306, and a metal ring 308. Fingerprint sensor detectorchip 304 can be fingerprint sensor detector chip 200 to include one ormore photodetection elements. In some embodiments however, the one ormore photodetection elements are located off of sensor chip 200 and onanother area of substrate carrier 302 cavity protective cover 306. Theprotective cover can be made of transparent materials, such as sapphireor zirconia. If there are cosmetic coloring applied to protective cover306, a transparent window may be used on protective cover 306 to allowlight to go through. Note that in this embodiment, protective cover 306covers the entire surfaces of sensor chip 304.

Fingerprint detection module 300 also includes one or more lightemitting sources 310 which can be placed within a cavity 312 of metalring 308. Light emitting sources 310 can include one or more lightemitting diode (LED) chips, one or more diode lasers, or one or moreother miniature light emitting devices. An exemplary LED chip in suchapplications can have an area of ˜200 μm×200 μm and a thickness of ˜200μm. In the embodiment shown, cavity 312 has a ring structure which isformed around the underside of metal ring 308. However, cavity 312 inmetal ring 308 can have many other configurations, for example, to onlypresent around the locations of light emitting sources 310.

Light emitting sources 310 can be configured to emit detection light ofdesirable wavelengths in response to a human finger or an object makingcontact with fingerprint detection module 300. For example, metal ring308 can serve as a sensing electrode to detect the contact from a humanfinger or an object. Light emitting sources 310 can emit light throughone or more light emitting windows which cut through metal ring 308 toconnect to cavity 312. In FIG. 3A, a light emitting window 314 islocated directly above one of the light emitting sources 310 insidecavity 312. In some embodiments, light emitting sources 310 include anmodulated light source.

FIG. 3B provides another perspective and cross-sectional view offingerprint detection module 300. FIG. 3C provides a perspective view ofentire fingerprint detection module 300.

FIG. 4 illustrates the concept of using a fingerprint detection module400 (which is substantially similar to fingerprint detection module 300)to detect and determine where a detected object is human. While FIG. 4is described in the context of fingerprint detection module 400, thetechniques described are general applicable to many variations offingerprint detection module 400, some of which will be described laterin the disclosure.

As mentioned above, fingerprint detection module 400 includes substratecarrier 402, protective layer 406, metal ring 408 and sensor chip 404,which may include a capacitive sense array for sensing a fingerprint'sridge and valley patterns. Fingerprint detection module 400 includeslight emitting sources 410 which reside within a cavity under metal ring408. In some implementations, light emitting sources 410 can emit atleast two different wavelengths through light emitting window 414 ofmetal ring 408. Fingerprint detection module 400 also includes one ormore photodetectors 416 which can either be integrated on sensor chip404 or separately placed on substrate carrier 402. In the embodimentshown, photodetectors 416 are located on an edge of sensor chip 404.

In some implementations, when an object 420 (not part of fingerprintdetection module 400) makes contact of fingerprint detection module 400,light emitting sources 410 emits detection light through light emittingwindow 414. The detection light is reflected off object 420 and thereflected light can be received and measured by photodetectors 416. Inparticular implementations, one or more wavelengths of detection lightare emitted by light emitting sources 410. For heartbeat detection, onewavelength of detection light is sufficient. For detecting touch fromactual human fingerprint, while one wavelength of detection light isenough, two or more wavelengths can be beneficial. For example, for onewavelength, the wavelength selected can be 660 nm. For two or morewavelengths, one wavelength selected can be 660 nm and the otherwavelength can be one of 905 nm, 910 nm or 940 nm. In anotherembodiments, the two wavelengths selected can be 590 nm and 805 nmrespectively. In yet another embodiments, the two wavelengths selectedcan be 520 nm and 575 nm. In some embodiments, only one wavelength isneeded and any one of the above identified wavelengths or otherwavelengths appropriate for the application (e.g., heartbeat detection)can be used.

FIG. 5A shows a data plot of normalized human skin reflectance (in %) asa function of the wavelength of the light source. Note that human skinhas different reflectance in response to different wavelengths and thisrelationship can be measured. As a result, the photodetector signalscorresponding to the reflected light from the two selected wavelengthscan be significantly different. In some implementations, photodetectors416 can be configured to measure the reflected light from bothwavelengths. The ratio of the two measurements can then be computed andcompared to a standard or calibrated value for human finger/skin todetermine if object 420 is human finger or not. The computation,comparison, and determination operations can be performed by an on-chipsignal processing unit such as signal processing unit 204 shown in FIG.2.

FIG. 5B shows a data plot of human blood light absorption property (inextinction coefficient) as a function of the wavelength of the lightsource. Note that human blood has different absorptions in response todifferent wavelengths. Moreover, for blood Hemoglobin lack of Oxygen(referred to as “Hb state”) and bound with Oxygen (referred to as “HbO2state”), the absorption behaviors are also significantly different. As aresult, the photodetector signals corresponding to the reflected lightfrom the two selected wavelengths can be significantly different, andthe photodetector signals corresponding to the reflected light from thesame wavelength under Hb or HbO2 state can also be significantlydifferent. In some implementations, photodetectors 416 can be configuredto measure the transmitted light through object 420 for bothwavelengths. The ratio of the two measurements can then be computed andcompared to a standard or calibrated value for human blood absorption todetermine if object 420 is human finger or not. The computation,comparison, and determination operations can be performed by an on-chipsignal processing unit such as signal processing unit 204 shown in FIG.2.

Photodetectors 416 can also be configured to measure the transmittedlight through object 420 for one or both wavelengths under both Hb stateand HbO2 state. The ratio of the two measurements at two differentwavelengths in each of the two states can then be computed and comparedto standard or calibrated values for human blood absorption to determineif object 420 is human finger or not. The computation, comparison, anddetermination operations can be performed by an on-chip signalprocessing unit such as signal processing unit 204 shown in FIG. 2.

The above measurements in FIG. 5A or 5B or both at the two differentoptical wavelengths can also be used to measure the person's heartbeatbased on the oxygen level in the blood due to pumping by the heart. Thetwo different wavelengths can be at the red spectral range and theinfrared spectral range, respectively. The heartbeat measurement is usedin some pulse oximeter devices or heart rate monitors based onmeasurements of the saturated level of oxygen in the blood. The relativeabsorption of red (absorbed by oxygenated blood) and infrared (absorbedby deoxygenated blood) light correlates to arterial blood oxygensaturations. Measurements of relative light absorption are made and areprocessed to generate the heart beat rate. This heart beat measurementprovides another check on whether the person is present when thefingerprint pattern is presented to the target device that is to beaccessed.

As mentioned above, a touch sensor within the fingerprint detectionmodule, such as metal ring 408 in fingerprint detection module 400 canbe used to detect the initial contact of an object, such as a user'sfinger. In one embodiment, the metal ring may be part of circuitry forinitial contact detection and module activation. In some embodiments,the fingerprint detection module can be in a standby mode (i.e., powersaving mode) before the detection of a new contact. Upon detecting a newcontact, the metal ring circuitry then activates the main circuit of thefingerprint detection module. When a current fingerprint detection andauthentication process is complete, the main circuitry of thefingerprint detection module can be turned off or deactivated and thefingerprint detection module returns to the standby mode while the metalring circuitry remains active and ready for next contact.

FIG. 6A presents a flowchart illustrating a process 600 of using afingerprint detection module to detect and determine if a detectedobject is human. The process 600 may be understood in the context offingerprint detection module 400. The process may begin when thefingerprint detection module detects an object is making contact withthe fingerprint detection module (602). In one embodiment, the metalring within the fingerprint detection module and associated circuit(e.g., metal ring 408 in module 400) may be used for the contactdetection. Note that light emitting sources within the fingerprintdetection module may be in off mode at this point and may be activatedby the detection of the contact. Light emitting sources within thefingerprint detection module start to emit detection light of twoselected wavelengths in response to the detection of contacting object(604). The one or more photodetectors within the fingerprint detectionmodule measure light signals which can include a portion of thedetection light reflected off of the contacting object and/or a portionof the detection light passing through (i.e., transmitted light) thecontacting object (606). Note that the portion of the detection lightpassing through the contacting object can be used to determine a lightabsorption property of the contacting object. A signal processing moduleprocesses the photodetector signals corresponding to the two selectedwavelengths, and determines whether the detected object is human bycomparing the computed signal ratios of the two selected wavelengthswith the characteristic values of the same parameters of a human finger(608). When the detection and authentication process is complete, thelight emitting sources may be turned off to save power (610).

As mentioned above, a metal ring within the fingerprint detectionmodule, such as metal ring 408 in fingerprint detection module 400 canbe used to detect the initial contact of a finger or an object. In oneembodiment, the metal ring may be part of a circuit for initial contactdetection and module activation. In some embodiments, the fingerprintdetection module can be in a standby mode (i.e., power saving mode)before the detection of a new contact. Upon detecting a new contact, themetal ring circuit then activates the main circuit of the fingerprintdetection module. When a current fingerprint detection andauthentication process is complete, the main circuit of the fingerprintdetection module can be turned off or deactivated and the fingerprintdetection module returns to the standby mode while the metal ringcircuit remains active and ready for next contact.

FIG. 6B presents a flowchart illustrating a process 620 of using afingerprint detection module (e.g., fingerprint detection module 400)having a metal ring circuit for fingerprint detection and authenticationin accordance with some embodiments described in this patent document.Before the process begins, the main fingerprint sensor and theassociated circuits (which can include the fingerprint sensor chip,and/or the light emitting sources and the photodetectors) of thefingerprint detection module are in standby mode (i.e., power savingmode), and only a metal ring circuit is functional or active. Note thatthe metal ring circuit includes both the metal ring as a sensor and anassociated circuit coupled to the metal ring to generate a detectionsignal when an object makes contact with the metal ring. The processbegins when the fingerprint detection module detects that an object ismaking contact with the fingerprint detection module based on adetection signal produced by the metal ring circuit (622). Next, thefingerprint detection module activates the main fingerprint sensor andassociated circuits, and gathers fingerprint sensor data (e.g., byscanning the object) (614). Fingerprint detection module then processesthe collected fingerprint sensor data to confirm the fingerprint isdetected (616). When the fingerprint detection module cannot confirm thefingerprint data at the process at 616, fingerprint detection module maycontinue to gather fingerprint sensor data. The fingerprint detectionmodule performs image processing on the gathered fingerprint data toverify whether the fingerprint data match the register fingerprint andeither authorizes or denies access (618). After authentication processis complete, the fingerprint detection module is switched to standbymode to save power, while the metal ring circuit remains active (620).

FIG. 7 presents a data flow diagram of an exemplary fingerprintdetection module 700 for performing human fingerprint detection andauthentication in accordance with some embodiments described in thispatent document. As shown in FIG. 7, fingerprint detection module 700includes a fingerprint pattern sensor 702 and an optical sensor module704, both of which are coupled to an authentication processor 706.Fingerprint pattern sensor 702 includes a sensor array which reads afingerprint pattern and a fingerprint pattern processor in communicationwith the sensor array to determine whether the fingerprint pattern readby the sensor array matches stored information of an authorized person'sfingerprint pattern to provide a fingerprint pattern authenticationoutput 708. Optical sensor module 704 produces probe light at one ormore optical wavelengths to which a person's skin produces differentoptical responses at the one or more optical wavelengths due to presenceof blood in the person's skin. Optical sensor module 704 also includesan optical detection unit that receives a reflection or transmission ofthe probe light to produce data indicative of optical measurements 710of the probe light at the one or more optical wavelengths. The produceddata indicative of optical measurements 710 are provided to theauthentication processor 706. The authentication processor 706 receivesthe fingerprint pattern authentication output 708 from fingerprintpattern sensor 702 and the optical measurements 710 data of the probelight at the one or more optical wavelengths from optical sensor module704 and to combine both fingerprint pattern authentication output 708and optical measurements 710 of the probe light to produce anauthentication output 712 which can be used to determine whether anaccess is to be granted or denied.

FIG. 8A is a schematic showing a cross sectional view of an exemplarymobile device 800 integrated with a touch screen assembly and afingerprint detection module. As shown in FIG. 8A, mobile device 800(e.g., a smartphone) includes a fingerprint detection module 802 havinga touch sensor such as a metal ring 804 positioned to be substantiallylevel with a surface of mobile device 800 parallel with a surface of topcover glass 806 exposed to the user. The touch sensor can be implementedusing any conductive material, such as any number of known metals. Inaddition, the shape of the touch sensor can vary based on the shape anddesign of the fingerprint detection module. The touch sensor can bedesigned to border at or near the outline of the fingerprint detectionmodule so as to substantially surround the portion of the fingerprintdetection module exposed to a user. For example, for a fingerprintdetection module in a round shape, a metal ring can be used as the touchsensor. For a fingerprint detection module shaped as a rectangle, thetouch sensor can be formed in the shape of a rectangular frame. The topcover glass 806 of mobile device 800 includes an opening to allowfingerprint detection module 802 to fit through and be exposed on thesurface. In addition, top glass 806 can be implemented using transparentmaterials other than glass including various crystalline structures,such as sapphire that provides the mobile device 800 with protectionwhile allowing at least visible light to pass through. Mobile device 800also includes a touch panel 808 and an LCD display module 810 positionedunderneath capacitive touch panel 808. Touch panel 808 can beimplemented using various touch technologies including a capacitivetouch sensor, an inductive touch sensor, and other touch sensors. Thetouch panel and the LCD display module 810 together form the touchscreen assembly. When mobile device 800 is locked, LCD display module810 is turned off and a main processor of mobile device 800 andfingerprint detection module 802 are in standby mode. To unlock mobiledevice 800, a user can make contact with the fingerprint detectionmodule 802 with the user's finger, for example. A touch sensor such asmetal ring 804 and associated circuitry communicatively coupled to themetal ring 804 can be used to detect a contact from an object 812 withthe fingerprint detection module 802. The touch sensor and associatedcircuitry can be used to activate fingerprint detection module 802responsive to a light contact, without additional user input through amechanical switch, such as actuating a physical button.

FIG. 8B is a schematic showing a cross sectional view of anotherexemplary mobile device 820 integrated with a touch screen assembly anda fingerprint detection module. Similar to mobile device 800 in FIG. 8A,mobile device 820 includes a fingerprint detection module 822 having atouch sensor, such as a metal ring 824. However, different from mobiledevice 800, the top cover glass 826 of mobile device 820 does not havean opening to expose the top surface (e.g., the surface exposed to theuser) of fingerprint detection module 822. Instead, fingerprintdetection module 822 is positioned underneath top cover glass 826 and isdesigned to sense a fingerprint of a finger without being directly incontact with the finger 832.

In the embodiment of FIG. 8B, top cover glass 826 protects touch panel828 and LCD display module 830 of the touch screen assembly and otherareas of a top surface of mobile device 820 substantially parallel withthe top cover glass 826 beyond the touch sensitive area associated withthe touch panel, including a location above fingerprint detection module822. Touch panel 828 is embedded within a support glass 834 underneathtop cover glass 826. Top cover glass 826 and support glass 834 can beimplemented using materials similar to top cover glass 806. Supportglass 834 includes an opening to allow fingerprint detection module 822to pass through and be placed under the top cover glass 826. Thelocation of the opening in support glass 834 may be closer to one end ofsupport glass 834, similar to the relative location of the opening intop cover glass 806 in FIG. 8A. The fingerprint detection module 822 inthis design can sense a contact from a fingerprint of a finger 832 witha top surface (e.g., the surface exposed to the user) of the hardenedtop cover glass 826 without having an object such as the finger 832being in direct contact with a surface on the fingerprint detectionmodule 822. This allows top cover glass 826 to fully cover both thetouch screen assembly and the fingerprint sensor under a spatiallycontiguous protective surface without an opening.

In one embodiment, top cover glass 826 and support glass 834 are bondedtogether to form an overall cover glass structure that is significantlythicker and mechanically stronger than each of top cover glass 826 andsupport glass 834 individually. The two glass layers may be bonded witha thin adhesive layer, such as an epoxy adhesive layer. The overallthickness of the combined structure may be comparable to top cover glass806 in FIG. 8A. Fingerprint detection module 822 which is positionedwithin the opening of support glass 834 may be directly attachedunderneath top cover glass 826.

In everyday uses when a user is holding or carrying mobile device 800 ormobile device 820 (e.g., in a pocket close to the body), unintended andincidental contacts on metal ring 804 or an surface area directly abovemetal ring 824 are common and can be difficult to avoid. Activation offingerprint detection module 802 or 822 and/or the main processor ofmobile device 800 or 820 from a standby mode due to unintended contactswith the touch sensor can negatively impact power consumption of amobile device. Devices, systems, and techniques described in variousembodiments of this document can potentially enable light contactactivation of fingerprint detection module 802 or 822 while preventingunintended contacts from activating the same fingerprint detectionmodule 802 or 822 and/or mobile device 800 or 820 from a standby mode.

FIG. 9A presents a flowchart illustrating an exemplary process 900 ofactivating a fingerprint detection module from standby mode and usingthe fingerprint detection module to authenticate a user's request togain access to a locked mobile device. The exemplary process 900 of FIG.9A is described with respect to fingerprint detection module 400 andmobile device 800 or 820. A fingerprint detection module (e.g.,fingerprint detection module 400) in standby mode has a touch sensorenabled to continuously receive from the touch sensor a touch sensorsignal (e.g., a metal ring signal from the metal ring touch sensor)indicating a contact from an object with the touch sensor (e.g., metalring) and the fingerprint detection module (902). In one embodiment, themetal ring touch sensor (e.g., metal ring 408 in module 400) of thefingerprint detection module and associated touch sensing circuitry(which may be integrated with sensor chip 404) are used for the contactdetection. For example, the associated touch sensing circuitry cangenerate a signal in response to an increase of capacitive load on themetal ring caused by an object, such as a finger, making contact withthe metal ring. Note that light emitting sources within the fingerprintdetection module are not enabled at this point. Until a metal ringsignal is detected at 902, the fingerprint detection module stays instandby mode waiting for the metal ring signal indicating a detectedcontact as shown in FIG. 9A.

Responsive to the fingerprint detection module receiving a metal ringsignal from the touch sensor and associated touch sensing circuitry, thefingerprint detection module activates an optical detection module andturns on light emitting sources, such as LEDs within the fingerprintdetection module to emit detection light of two selected wavelengths(904). The optical detection module includes one or more photodetectorswithin the fingerprint detection module (e.g., photodetector 416 inmodule 400) to measure optical signals associated with the emitteddetection light reflecting off of the contacting object and/or theemitted detection light passing through (i.e., transmitted light) thecontacting object (906). The detection light passing through thecontacting object can be used to determine a light absorption propertyof the contacting object. A signal processing module processesphotodetector signals corresponding to the measured optical signals intwo predetermined wavelengths. Based at least partially on the processedphotodetector signals, the signal processing module determines whetherthe detected contact is from human skin by comparing computed signalratios of the processed photodetector signals at two selectedwavelengths with the characteristic values of the same parameters ofhuman skin (908). In some implementations, the optical detection moduleis integrated with the fingerprint sensor chip.

When the determination at 908 is that the detected contact is not fromhuman skin, the fingerprint detection module is switched back to thestandby mode (902). For example, the detected contact could be based ona non-human-skin object making contact with the metal ring, such ashuman body touching the metal ring through clothing. In oneimplementation, returning to the standby mode also involves turning offthe light emitting sources. However, when the determination at 908 isthat the detected contact is from human skin, the fingerprint detectionmodule activates the main fingerprint sensor and the associatedcircuitry in the fingerprint detection module, and begins obtainingfingerprint sensor data from the human skin (910).

The fingerprint detection module processes the obtained fingerprintsensor data to determine whether a human fingerprint is detected (912).This is performed prior to full fingerprint verification to distinguisha human fingerprint from another part of human skin, such as anotherpart of a human hand, human arm, and human face, making contact with thefingerprint detection module. In some implementations, the initialdetermination of human fingerprint at 912 does not obtain and processthe full fingerprint data in order to save power and processing time.For example, the fingerprint sensor measures one-directional (1D) humanskin profile and associated detection circuitry determines whether themeasured 1D skin profile substantially matches a human fingerprint. Thedetection circuitry associated with the fingerprint sensor can comparethe measured 1D skin profile with a typically 1D fingerprint contourthat includes a periodic ridge and valley pattern and determine whetherthe measured 1D skin profile resembles a human fingerprint. Moreover,the detection circuitry used to perform the initial determination ofhuman fingerprint at 912 can be low power detection circuitry within thefingerprint detection module, for example, circuitry integrated with thesensor chip. As such, performing the initial determination of humanfingerprint at 912 does not require the main processor (e.g., theapplication processor) of the mobile device, which can remain in standbymode until full fingerprint verification is needed. Using partialfingerprint data and low power circuitry can ensure low powerconsumption at 910 and 912.

When the determination at 912 is that a human fingerprint is notdetected from the human skin, the fingerprint detection module again isswitched back to the standby mode at 902. For example, the detectedcontact from human skin without a human fingerprint can be the result ofa contact from a side of the user's hand, arm or face with the metalring. In one implementation, returning to the standby mode of 902 alsoincludes turning off the light emitting sources.

When the determination at 912 is that the detected contact is from ahuman fingerprint, the fingerprint detection module then obtains fullfingerprint data with the fingerprint sensor and sends the obtained fullfingerprint data to the main processing unit for processing (914), whichmay involve waking up the main processing unit from the standby mode.The full fingerprint sensor data is processed by the main processingunit to verify whether the obtained full fingerprint data match thestored fingerprint data of an authorized user of the mobile device.Based on the outcome of the verification, the main processing unitauthorizes or denies user access to the locked mobile device (916). Thefingerprint detection module is switched back to the standby mode at 902if access is denied. Otherwise, if the access is granted, thefingerprint detection module is also switched back to the standby modebut does not return back to 902.

FIG. 9B presents a flowchart illustrating an exemplary process 901 ofauthenticating user request to access a locked mobile device in a highsecurity mode based on a combination of fingerprint detection andoptical heartbeat detection. The process 901 illustrated in FIG. 9Bincludes a fingerprint detection process which is substantially similarto the process 900 of FIG. 9A from (902) to (914). The full fingerprintsensor data obtained (914) is processed to verify whether the obtainedfingerprint data match the stored fingerprint data of an authorized userof the locked mobile device (926). When no match is found, the userrequest to access the mobile device is denied and the fingerprintdetection module is switched back to the standby mode (902). When amatch is verified, the fingerprint detection module activates an opticaldetection module including the light emitting sources and thephotodetectors to detect the presence of human heartbeat signals (928).Detecting the presence of human heartbeat signal can be performed withor without determining the actual heart beat rate. As described above,the two optical wavelengths emitted by the light emitting sources can beused to measure a user's heartbeat based on the oxygen level in theblood due to pumping of the heart. This heartbeat measurement offers anadditional check on whether a live person is associated with thedetected human fingerprint.

When the presence of a heartbeat signal is detected (930), the userrequest to access the locked mobile device is granted and thefingerprint detection module is switched back to a standby mode (932).Otherwise, the user request to access the locked mobile device is deniedand the fingerprint detection module is switched back to the standbymode (902). Combining heartbeat detection with the fingerprint detectionprovides an added layer of security to the user authenticationprocedure.

FIG. 10 presents a flowchart illustrating another exemplary process 1000of authenticating user request to access a locked mobile device in ahigh security mode based on a combination of fingerprint detection andoptical heartbeat detection.

A fingerprint detection module in a standby mode can continuouslymonitors for a contact from an object with the fingerprint detectionmodule (1002). When the fingerprint detection module detects a contactfrom an object with the fingerprint detection module, the fingerprintdetection module is used to determine whether the detected contact isfrom human skin (1004). In absence of contact from human skin, thefingerprint detection module returns to standby mode and continues tomonitor for another contact (1002). When a contact from human skin isdetected, the fingerprint detection module obtains data from the objectmaking contact to determine whether the data from the object resembleshuman fingerprint (1006). In absence of fingerprint detection, thefingerprint detection module returns to standby mode and continues tomonitor for the next contact (1002). When the detected contact isdetermined to be from human fingerprint, the main processing unitattempts to authenticate the obtained fingerprint data to determinewhether the obtained fingerprint data match the stored fingerprintpatterns of an authorized user of the mobile device (1008). When theobtained fingerprint data does not match with the stored fingerprintpattern of the authorized user of the mobile device, the fingerprintdetection module returns to standby mode and continues to monitor forthe next contact (1002). When the obtained fingerprint data match thestored fingerprint pattern of an authorized user of the mobile device,the fingerprint detection module determines whether the detectedfingerprint of an authorized user of the mobile device is associatedwith a live human by detecting a presence of a heartbeat signal (1010).When the presence of a heartbeat signal is detect, the user request toaccess the locked mobile device is granted. When the presence of aheartbeat is not detected, the user request to access the locked mobiledevice is denied and the fingerprint detection module returns to standbymode and continues to wait for the next contact (1002). In variousembodiments, the added verification of the heartbeat signal detectionassociated with the authorized user fingerprint detection at 1010 can beimplemented as an optional process and the user request to access thelocked mobile device can be granted or denied based solely on thedetection of an authorized user's fingerprint at 1008. In someimplementations, the user authentication process 1000 can directlyobtain fingerprint data from the object making contact without one orboth intermediate processes of identifying the detected contact as beingfrom human skin (1004) and determining whether fingerprints can be foundon the identified human skin (1006). In some other implementations, theheartbeat detection process (1010) may be performed after detecting acontact from an object (1002) but before determining whether fingerprintdata of an authorized user can be detected on the human skin makingcontact with the touch sensor of the fingerprint detector (1008).

FIG. 11A illustrates an exemplary fingerprint detection module 1100 as avariation of fingerprint detection module 400 for determining whether adetected contact from an object is from human skin.

Similarly to fingerprint detection module 400, fingerprint detectionmodule 1100 includes substrate carrier 1102, protective cover 1106,touch sensor such as a metal ring 1108 and sensor chip 1104, which mayinclude a capacitive sense array for sensing a fingerprint's ridge andvalley patterns. Also, fingerprint detection module 1100 includes one ormore photodetectors 1116 which can either be integrated on sensor chip1104 or separately placed on substrate carrier 1102. The touch sensorfor detecting a contact from an object can be implemented usingconductive material having a shape corresponding to the fingerprintdetection module, such as a metal ring 1108 placed around and slightlyabove the protective cover to protect the border of the protectivecover. The touch sensor can serve as a sensing electrode to detect acontact from an object 1120 with the fingerprint detection module 1100.In fingerprint detection module 1100, one or more light emitting sources1110 are located directly under protective cover 1106 within a gapbetween protective cover 1106 and substrate carrier 1102 and close to anedge of sensor chip 1104. Thus, unlike the fingerprint detection module400, the metal ring 1108 in fingerprint detection module 1100 does notinclude a cavity for housing the light emitting sources 1110. In someimplementations, light emitting sources 1110 can emit at least twodifferent wavelengths.

To allow detection light signals emitted from light emitting sources1110 to pass through protective cover 1106 and reach object 1120, theprotective cover 1106 is transparent to the detection lights. Whenprotective cover 1106 is coated with a colored layer on the bottomsurface to achieve a desired appearance, the colored layer can be opaqueto the wavelengths of lights emitted by light emitting sources 1110,which are placed directly underneath the colored layer.

FIG. 11B illustrates an exemplary fingerprint detection module 1101which includes a protective cover coated with a colored layer. As can beseen in FIG. 11B, fingerprint detection module 1101 includes substratecarrier 1102, sensor chip 1104, protective cover 1106, metal ring 1108,one or more light emitting sources 1110 located underneath protectivecover 1106, and one or more photodetectors 1116. A colored layer 1112 iscoated on the bottom surface of protective cover 1106 to provide theintended color appearance. The color layer 1112 is transparent to thelight emitted from light emitting sources 1110 to allow the emittedlight to pass through the colored layer 1112 and reach an object makingcontact with protective cover 1106. Moreover, the color layer 1112 istransparent to reflected light from the object making contact with theprotective cover 1106 to reach photodetectors 1116 which is also locatedunderneath colored layer 1112. In the embodiment shown in FIG. 11B,transparency to emitted light and reflected light is achieved usingmultiple micro-holes 1114 created through colored layer 1112 in theregions directly above light emitting sources 1110 and photodetectors1116. These micro-holes 1114 can be sufficiently small so that they arenot visible to a user but large enough to allow emitted light from lightemitting sources 1110 to pass through and reach an object and reflectedlight from an object to pass though and reach photodetectors 1116. Forexample, the size of the multiple micro-holes can be from about 1 μm toa few μm. In some implementations, micro-holes 1114 are formed in thecolored layer 1112 using a laser.

In various embodiments of a fingerprint detection module described inthis patent document (i.e., fingerprint detection modules 100, 300, 400,1100, and 1101), the fingerprint sensor chip in a respective fingerprintdetection module can have a thickness between 200 μm to 500 μm. Thesubstrate in a respective fingerprint detection module can have athickness between 0.5 mm to 2 mm. The metal ring in a respectivefingerprint detection module can have a thickness between 0.5 mm to 2mm. The thickness of the protective cover in a respective fingerprintdetection module can be between 100 μm to 500 μm. The protective cover,e.g., protective cover 106, can be made of entirely by a singlematerial, e.g., sapphire, zirconia, or ceramic. However, in someimplementations, a protective cover can be made of at least two layers:a top layer of a relatively hard and more expensive material of highdielectric-constant (e.g., sapphire, zirconia, or diamond-like carbon)and a bottom layer of relatively less expensive material of highdielectric-constant (e.g., a ceramic material such as aluminum nitride(AlN)). For example, if a protective cover has an overall thickness of450 μm, the top layer can be made of 150 μm of sapphire and the bottomlayer can be made of 300 μm AlN. Such double layer structure can lowerthe overall cost of the protective cover while maintaining sufficientlyhigh hardness and dielectric strength.

FIG. 12 presents a diagram of an exemplary fingerprint detection system1200 for performing human fingerprint detection and authentication. Asshown in FIG. 12, fingerprint detection system 1200 includes a touchsensing module 1202 which includes a touch sensor (such as a metal ring)and sensor circuitry for detecting a contact from an object withfingerprint detection system 1200. Also, fingerprint detection system1200 includes an optical sensor module 1204, a fingerprint patternsensor 1206, and an authentication processor 1208. Touch sensing module1202 is communicatively coupled to optical sensor module 1204 to combinesensor data from touch and optical sensors. When touch sensing module1202 detects a contact from an object, such as a finger, touch sensingmodule 1202 activates optical sensor module 1204 to perform fingerprintanalysis. Optical sensor module 1204 produces probe light at two or moredifferent optical wavelengths to which a person's skin producesdifferent optical responses at the two or more different opticalwavelengths due to presence of blood in the person's skin. An opticaldetection unit in the optical sensor module 1204 receives a reflectionor transmission of the probe light from the object making contact todetect optical measurements that represent reactions of the reflectedprobe light at the two or more different optical wavelengths. Theoptical measurements of the reflected probe at different wavelengths canbe used to compute values that are compared to standard or calibratedvalues for human blood absorption to determine whether the detectedcontact is from human skin. The computation, comparison, anddetermination of reflected probe light operations can be performed by anon-chip signal processing unit integrated with optical sensor module1204.

Optical sensor module 1204 is communicatively coupled to fingerprintpattern sensor 1206. When optical sensor module 1204 detects human skinas the object making contact, optical sensor module 1204 activatesfingerprint pattern sensor 1206. Fingerprint pattern sensor 1206includes a sensor array which obtains fingerprint data and a fingerprintpattern processor that determines whether the obtained fingerprint dataresembles a human fingerprint. Fingerprint pattern sensor 1206 iscommunicatively coupled to authentication processor 1208. Whenfingerprint pattern sensor 1206 detects a human fingerprint, fingerprintpattern sensor 1206 activates authentication processor 1208.Authentication processor 1208 receives the obtained fingerprint datafrom fingerprint pattern sensor 1206 and verifies whether the obtainedfingerprint data matches stored fingerprint data of an authorizedperson's fingerprint pattern. Based on the verification outcome, theauthentication processor generates authorization decision 1210 todetermine whether the user request to access the locked mobile device isgranted or denied.

In a high security operation mode, authentication processor 1208 canreceive optical measurements at two or more optical wavelengths fromoptical sensor module 1204, and used the optical measurements to detecta presence of a human heartbeat signal. This heartbeat detection offersan additional layer of security on whether a live person is associatedwith the detected human fingerprint. The authentication processor 1208then generates authorization decision 1210 based on both the result offingerprint authentication and the result of heartbeat detection.

FIG. 13A is a top-down view of an exemplary mobile device 1300 showing atouch sensor assembly packaged under a display screen cover glass. Themobile device 1300 includes a display screen cover glass 1310 with anexemplary thickness between 0.55-0.75 mm. The touch sensor assembly 1312is packaged to be disposed under the display screen cover glass 1310.FIG. 13B is a cross sectional view of the mobile device 1300 cut alongthe line A-A. A cross-sectional view of the display screen cover glass1310 is shown with a cross-sectional view of the touch sensor assemblysection 1312 packaged or disposed under the display screen cover glass1310.

FIG. 13C shows a cross-sectional view of the touch sensor assembly 1312shown in FIGS. 13A and 13B packaged to be under or flush with thedisplay screen cover glass 1310. The display screen cover glass 1310 canhave a thickness between 0.55-0.75 mm. The touch sensor assembly 1312includes a sensor chip 1332 with an exemplary thickness of 0.25 mm. Thesensor chip 1332 is disposed over a printed circuit board (PCB) 1334having an exemplary thickness between 0.3-0.5 mm. A filling material,such as epoxy etc. 1340 can be disposed between the sensor chip 1332 andthe PCB 1334 to attach the sensor chip 1332 to the PCB 1334. A sensorcover glass 1330 with an exemplary thickness of between 0.1-0.3 mm canbe disposed over the sensor chip 1332. The sensor cover glass 1330 canincorporate a desired color to achieve a desired visual appearance. Aflexible printed circuit (FPC) connector 1336 can be glued onto thesensor cover glass 1330 between the sensor cover glass 1330 and thesensor chip 1332. The sensor cover glass 1330 can have an exemplarythickness of approximately 0.03 mm. In addition a filling material 1338,such as epoxy etc. can be disposed between the FPC connector 1336 andthe sensor chip 1332. A metal layer 1342 can be bound to each side ofthe sensor cover glass 1330 and connected to the TX of the sensor chip1330. One or more compressed solder balls 1346 can be disposed on theedges of the sensor chip 1332 between the FPC connector 1336 and thesensor chip 1332. One or more solder balls 1344 can be disposed betweenthe FPC connector 1336 and the filling material, such as epoxy etc. 1340disposed over the PCB 1334.

The packaging of the touch sensor assembly shown in FIGS. 13A, 13B and13C can be applied to fingerprint detection modules 100, 300, 400, 1100and 1101 in addition to mobile devices 800 and 820.

In one aspect, a fingerprint detection module includes a substratecarrier and a fingerprint sensor chip located on the substrate carrierfor collecting fingerprint data. The fingerprint detection module alsoincludes one or more light emitting sources located on the substratecarrier and configured to emit detection light comprising at least onewavelength. The fingerprint detection module additionally includes atleast one photodetection element located on the substrate carrier andconfigured to receive and detect at least a portion of the detectionlight which is reflected off of an object making contact with thefingerprint sensor module. The at least one photodetection elementgenerates output signals in response to the detected light, wherein theoutput signals are used to determine if the object is human.

In some implementations, the at least one photodetection element isintegrated on the fingerprint sensor chip. For example, the at least onephotodetection element can be located at an edge of the fingerprintsensor chip. In some other implementations, the at least onephotodetection element is separated from the fingerprint sensor chip andlocated on a different area of the substrate carrier.

In some implementations, the one or more light emitting sources includeone or more light emitting diode (LED) chips. The one or more lightemitting sources can emit the detection light in response to thedetection that an object is making contact with the fingerprint sensormodule. Moreover, the at least one photodetection element can beconfigured to detect a portion of the detection light which passesthrough the object making contact with the fingerprint sensor module,wherein the detected light can be used to determine a light absorptionproperty of the object. The one or more light emitting sources can bemodulated light sources.

In some implementations, the fingerprint sensor chip includes apixelated sensing element array and a signal processing unit forprocessing the collected fingerprint data. The signal processing unitcan be configured to process two output signals generated by the atleast one photodetection element corresponding to the at least onewavelength of light. For example, the signal processing unit can computea ratio of the two output signals and compare the computed ratio with apredetermined value calibrated for a human finger or human skin todetermine if the object is human.

In some implementations, the fingerprint detection module additionallyincludes a protective cover placed over the fingerprint sensor chip toprotect the fingerprint sensor chip and a metal ring placed around andslightly above the protective cover to protect the border of theprotective cover. The one or more light emitting sources can be placedinside a cavity within the metal ring, and to emit the detection lightthrough one or more windows located at the top of the metal ring.Furthermore, the metal ring can serve as a sensing electrode to detectif the object is making contact with the fingerprint sensor module.

In some implementations, the substrate carrier can have a thicknessbetween 0.5 mm to 2 mm. The fingerprint sensor chip can have a thicknessbetween 200 μm to 500 μm. The protective cover chip can have a thicknessbetween 100 μm to 500 μm. The metal ring can have a thickness between0.5 mm to 2 mm.

In another aspect, a fingerprint sensor module includes a substratecarrier and a fingerprint sensor chip located on the substrate carrierfor collecting fingerprint data. The fingerprint sensor module alsoincludes a protective cover placed over the fingerprint sensor chip toprotect the fingerprint sensor chip. The fingerprint sensor moduleadditionally includes a high dielectric-constant layer sandwichedbetween the protective cover and the fingerprint sensor chip to separatethe protective cover and the fingerprint sensor chip. Moreover, at leastone edge of the fingerprint sensor chip is extended beyond the boundaryof the high dielectric-constant layer to create a space between theprotective cover and the fingerprint sensor chip for wire-bonding thefingerprint sensor chip.

In some implementations, the high dielectric-constant layer is made of aceramic material having a dielectric constant greater than 8. Forexample, the high dielectric-constant layer can be made of a ceramicmaterial having a dielectric constant between 20 to 30. The thickness ofthe high dielectric-constant layer can be greater than 100 μm.

In another aspect, a fingerprint sensor module includes a substratecarrier and a fingerprint sensor chip located on the substrate carrierfor collecting fingerprint data. The fingerprint sensor module alsoincludes a protective cover placed over the fingerprint sensor chip toprotect the fingerprint sensor chip, wherein at least one edge of thefingerprint sensor chip is extended beyond the border of the protectivecover to allow wire-bonding directly over the at least one edge of thefingerprint sensor chip without getting interference from the protectivecover.

In yet another aspect, a fingerprint sensor module includes a substratecarrier and a fingerprint sensor chip located on the substrate carrierfor collecting fingerprint data. The fingerprint sensor module alsoincludes a protective cover placed over the fingerprint sensor chip toprotect the fingerprint sensor chip, wherein the protective covercomprises at least two layers: a top layer made of a hard and moreexpensive material of high dielectric-constant and a bottom layer madeof a less expensive material of high dielectric-constant. The top layercan be significantly thinner than the bottom layer.

In yet another aspect, a fingerprint detection module includes asubstrate carrier and a fingerprint sensor chip located on the substratecarrier for collecting fingerprint data. The fingerprint detectionmodule also includes one or more light emitting sources located on thesubstrate carrier and configured to emit detection light comprising atleast one wavelength. The fingerprint detection module additionallyincludes at least one photodetection element located on the substratecarrier and configured to detect at least a portion of the detectionlight which is reflected off of an object making contact with thefingerprint sensor module, wherein output signals from the at least onephotodetection element in response to the detected light are used todetermine if the object is human. The fingerprint detection modulefurther includes a protective cover placed over the fingerprint sensorchip to protect the fingerprint sensor chip. Moreover, the fingerprintdetection module includes a high dielectric-constant layer sandwichedbetween the protective cover and the fingerprint sensor chip to separatethe protective cover and the fingerprint sensor chip, wherein at leastone edge of the fingerprint sensor chip is extended beyond the boundaryof the high dielectric-constant layer to create a space between theprotective cover and the fingerprint sensor chip for wire-bonding thefingerprint sensor chip.

In yet another aspect, a method for determining if an object makingcontact with a fingerprint detection module is human is described. Themethod includes the steps of: in response to the detection of an objectis making contact with the fingerprint detection module, emittingdetection light of at least two selected wavelengths using one or morelight emitting sources within the fingerprint detection module;detecting at least a portion of the detection light which is reflectedoff of the object making contact with the fingerprint sensor moduleusing at least one photodetection element within the fingerprintdetection module; processing the output signals from the at least onephotodetection element corresponding to the two selected wavelengths;and determining whether the detected object is human by comparing asignal ratio corresponding to the two selected wavelengths with apredetermined value of the same signal ratio calibrated from a human.

Various examples of fingerprint detection modules and fingerprint sensormodules described in this patent document can be integrated with mobiledevices (e.g., smartphones, tablets, laptops), computing devices (e.g.,personal computers), and other electronic devices to perform fingerprintauthentication processes on these devices.

Techniques, systems, and devices are disclosed for performing humanfingerprint detection and authentication using an optical detectionmodule in addition to a fingerprint pattern recognition sensor. Thedisclosed human fingerprint detection and authentication technology canbe integrated with mobile devices (e.g., smartphones and tablets) andother devices (e.g., such as computer monitors) to improve thefingerprint authentication technology used in existing devices.

While this patent document contains many specifics, these should not beconstrued as limitations on the scope of any invention or of what may beclaimed, but rather as descriptions of features that may be specific toparticular embodiments of particular inventions. Certain features thatare described in this patent document in the context of separateembodiments can also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment can also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Moreover, the separation of various system components in theembodiments described in this patent document should not be understoodas requiring such separation in all embodiments.

Only a few implementations and examples are described and otherimplementations, enhancements and variations can be made based on whatis described and illustrated in this patent document.

What is claimed is:
 1. A fingerprint detection module, comprising: a printed circuit board; a fingerprint sensor chip disposed over the printed circuit board and configured to collect fingerprint data; a protective layer disposed over the fingerprint sensor chip to protect the fingerprint sensor chip; a touch sensor disposed substantially next to the protective layer to detect a contact from an object making contact with the fingerprint detection module; and an optical detection module that includes: one or more light emitting sources located on a substrate carrier and underneath the protective layer; at least one photodetection element integrated with the fingerprint sensor chip and underneath the protective layer; and a signal processing circuit integrated with the fingerprint sensor chip.
 2. The fingerprint detection module of claim 1, wherein the touch sensor comprises a conductive electrode.
 3. The fingerprint detection module of claim 1, further comprising touch sensing circuitry communicatively coupled to the touch sensor to detect a signal indicative of the object in contact with the touch sensor.
 4. The fingerprint detection module of claim 3, wherein the touch sensing circuitry is configured to detect a contact from the object by detecting an increase in a capacitive load coupled to the conductive electrode.
 5. The fingerprint detection module of claim 4, further comprising detection circuitry integrated with the fingerprint sensor chip to detect a presence of fingerprint data from the object.
 6. The fingerprint detection module of claim 1, further comprising a colored layer coated on the bottom surface of the protective cover, wherein the colored layer contains micro-holes in a first region directly above the one or more light emitting sources and a second region directly above the at least one photodetection element to allow light to pass through the colored layer in the first region and the second region.
 7. The fingerprint detection module of claim 1, further comprising a colored layer coated on the bottom surface of the protective layer, wherein the colored layer is transparent with a nonvisual wavelength light in a first region directly above the one or more light emitting sources and a second region directly above the at least one photodetection element to allow certainly wavelength light to pass through the colored layer in the first region and the second region.
 8. The fingerprint detection module of claim 1, wherein the one or more light emitting sources are configured to emit detection light comprising at least one wavelength; and wherein the at least one photodetection element are configured to receive and detect at least a portion of the detection light which is reflected off of an object making contact with the fingerprint detection module.
 9. The fingerprint detection module of claim 8, wherein output signals from the at least one photodetection element in response to the detected light are used to determine one or both of: whether the detected contact from the object is from human skin; and whether a presence of a heart beat is detected from the object.
 10. The fingerprint detection module of claim 1, wherein the module is configured to combine the collected fingerprint data from the fingerprint sensor chip and the detected contact from the touch sensor to deny a person's access when the collected fingerprint data matches stored fingerprint data of an authorized user's fingerprint pattern while the detected contact fails to indicate the contact is from a live person.
 11. The fingerprint detection module of claim 1, further including: an authentication processor coupled to the fingerprint sensor chip and the touch sensor and is configured to combine the collected fingerprint data from the fingerprint sensor chip and the detected contact from the touch sensor to authenticate a person when the collected fingerprint data matches stored fingerprint data of an authorized user's fingerprint pattern and the detected contact indicates the contact is from a live person.
 12. A fingerprint detection module, comprising: a touch sensor including a metal ring configured to detect a contact from an object making contact with the fingerprint detection module; a fingerprint pattern sensor that includes a sensor array configured to read a fingerprint pattern and a fingerprint pattern processor configured to determine whether the read fingerprint pattern matches stored information of an authorized user's fingerprint pattern to provide a fingerprint pattern authentication output; an optical sensor module that produces probe light at one or more optical wavelengths to which the user's skin produces different optical responses at the one or more optical wavelengths due to presence of blood under the skin, the optical sensor module including an optical detection unit configured to receive a reflection or transmission of the probe light to produce optical measurements of the probe light at the one or more different optical wavelengths; and an authentication processor configured to receive the fingerprint pattern authentication output from the fingerprint pattern sensor and the optical measurements of the probe light at the one or more different optical wavelengths from the optical sensor module and to combine both the fingerprint pattern authentication output and optical measurements of the probe light to determine whether an access is to be granted or denied.
 13. The fingerprint detection module of claim 12, wherein: the authentication processor is configured to combine the collected fingerprint data from the fingerprint sensor chip and the detected contact from the touch sensor to authenticate a person when the collected fingerprint data matches stored fingerprint data of an authorized user's fingerprint pattern and the detected contact indicates the contact is from a live person, and to deny a person's access when the collected fingerprint data matches stored fingerprint data of an authorized user's fingerprint pattern while the detected contact fails to indicate the contact is from a live person.
 14. The fingerprint detection module of claim 1, wherein the touch sensor includes a metal ring configured to detect the contact.
 15. The fingerprint detection module of claim 1, further comprising: a fingerprint pattern sensor that includes a sensor array configured to read a fingerprint pattern and a fingerprint pattern processor configured to determine whether the read fingerprint pattern matches stored information of an authorized user's fingerprint pattern to provide a fingerprint pattern authentication output.
 16. The fingerprint detection module of claim 15, further comprising: an authentication processor configured to receive the fingerprint pattern authentication output from the fingerprint pattern sensor and the optical measurements of the probe light at the one or more different optical wavelengths from the optical sensor module and to combine both the fingerprint pattern authentication output and optical measurements of the probe light to determine whether an access is to be granted or denied.
 17. The fingerprint detection module of claim 1, further comprising: an optical sensor module that produces probe light at one or more optical wavelengths to which the user's skin produces different optical responses at the one or more optical wavelengths due to presence of blood under the skin, the optical sensor module including an optical detection unit configured to receive a reflection or transmission of the probe light to produce optical measurements of the probe light at the one or more different optical wavelengths. 